textproduct: Quad Cities

KEY MESSAGES

- Active weather through midweek, as a storm system brings along the chance for heavy rainfall and a low-end severe threat. Higher confidence will be on the rainfall potential, lower on the severe threat.

- Seasonal temperatures will remain through the week, with temperatures and humidity on the rise this upcoming weekend.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 154 PM CDT Mon Aug 3 2026

Another beautiful afternoon and evening will be seen, with seasonal temperatures in the 80s, light winds, and a mix of clouds/sun. Daytime diurnal Cu will burn off this evening, leaving us mostly clear for the first half of the night, with mid-high clouds moving into the northwest by sunrise. Warm advection will gradually increase overnight, which will help keep temperatures in the low-mid 60s.

Tuesday into Tuesday night, we will see the transition from tranquil to active weather. A broad upper trof over the central CONUS will guide bouts of energy through the region, with the first coming through midday Tuesday. With this, a weak cold front will slowly move into the area from the northwest. Overall, much of the day will remain dry, with better moisture/forcing moving in Tuesday afternoon and evening. Instability and shear seems to be meager at this point, largely favoring unorganized showers/storms in our north during the afternoon and early evening. As we get later in the evening, this cold front will eventually stall out over the area, roughly near the HWY 30 and I-80 corridors. As this front stalls, we will continue to see weak bouts of energy flow along the base of the broad upper trof, as well as a subtle LLJ increase. All of these features will act together to generate showers/storms for much of Tuesday night. The heaviest rainfall will generally be focused along the stalled out boundary, where repeated rounds of storms can be expected.

Coverage will increase shortly after sunset, where we may see a complex of storms move in from the west, with continual development behind that for the remainder of the night. While we are not outlooked for severe weather at this time, a look at model soundings would indicate a low-end potential for strong to severe storms. This would mainly be focused on the initial complex of storms moving in mid-evening, with severe chances after midnight low. If we do end up seeing strong to severe storms, severe wind gusts would be the main concern. As was mentioned above, there is the chance for heavy rainfall due to repeating rounds of storms. Short term guidance favors PWATs between 1.75-2.00" or higher, especially overnight Tuesday into Wednesday. These values are well above seasonal norms, which would favor the heavy rain potential. Current guidance would indicate the potential for 1.00-2.00" of rain overnight Tuesday for areas along the front, with <1.00" for less hit areas. Locally higher amounts are possible under the heavier rainfall axis. Currently, the axis with greatest potential of repeating storms is roughly along/south of a line from Freeport IL to Fairfield IA. This axis of heavier rainfall is likely to shift some over the next day, as guidance does not have a great grasp on the location at this time. The ground should largely have enough storage for the heavier rainfall, but there will be a low-end flash flood threat, especially for urban areas.

LONG TERM /WEDNESDAY THROUGH MONDAY/

Issued at 154 PM CDT Mon Aug 3 2026

Wednesday-Thursday...A stronger shortwave trough will swing into the base of the longwave situated over the Upper Mississippi River Valley on Wednesday, finally pushing the cold front further southeast along with the scattered showers and storms. Areas that receive repeated rounds of storms, especially after rainfall Tuesday night, could see some localized flash flooding which is why the WPC has issued a Slight Risk (level 2 out of 4) for excessive rainfall for most of the CWA. Along and ahead of the front on Wednesday, we may see the chance for strong to severe storms as well. Overall, confidence is low, owing to weaker shear/instability. The SPC has highlighted areas along/south of Highway 34 in a Marginal Risk (level 1 of 5) on Wednesday. Primary hazard with any storm would be severe wind gusts. By Wednesday night, a high pressure shifts into the CWA as convergence aloft continues to dry things out. Isolated showers and storms (20-30% coverage) could stick around in northeast Missouri and west-central Illinois along an area of low-level isentropic upglide near the baroclinic zone into Thursday morning.

Friday-Sunday...The longwave trough axis propagates into the Great Lakes region, providing additional ageostrophic convergence aloft Friday into Saturday. As the high pressure over the region moves eastward, southerly flow will likely return into the weekend and advect in some warmer and more moist air. Highs could climb back into the upper 80s and low 90s by Sunday (50-80% chance for 90 in our southwest, lower probs north, per 03.00z LREF run). Precipitation chances have trended down for the weekend, with PoPs returning to the area Sunday night through Monday.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 645 PM CDT Mon Aug 3 2026

Predominantly VFR conditions are expected through the TAF cycle. Wildfire smoke will be found across the region, but should remain aloft and not impact surface visibility. Pockets of fog can't be ruled out 08z-13z, but confidence is low with extent and development at the terminals. The greater signal for fog is mainly east of the terminals within very weak surface flow near the retreating surface ridge. We'll reside on the backside of the ridge within light southeast flow 4-8 kt, which may provide just enough BL mixing to preclude widespread fog thereby compounding the low confidence with coverage/ placement and magnitude of fog to where any mention was left out for now. Showers and storms are expected to develop along a cold front in the Plains and move east, eventually weakening while approaching eastern Iowa Tuesday mid morning to midday with the probability (<25%) for precipitation too low to include. There is a growing consensus that the cold front aided by convection will make inroads into the area Tuesday afternoon and reside near KDBQ to KCID. This front and an upper level disturbance will provide the potential for widely scattered shra/tsra and have kept PROB30 tsra mention confined to KDBQ and KCID in close proximity to the boundary. Winds will likely veer to westerly at both sites in the afternoon, while winds at KMLI and KBRL will remain southerly and peaking around 10 kt sustained with some localized higher gusts possible.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.